Our in vitro studies in which we have applied techniques derived from oscillator theory to examine the dynamic behavior of the LUQ neurons and the ways in which synaptic input can control this activity are now in press. We have made substantial progress in the computer programming for our phase plane studies. Our goals of the coming year are (1) to utilize autoradiography to determine the peripheral sites of termination of the LUQ neurons, and (2) to extend our chronic in vivo studies of the natural firing patterns of these neurons under various experimental conditions. BIBLIOGRAPHIC REFERENCES: Pinsker, H. and Kandel, E. 1977. Short-term modulation of endogenous bursting rhythms by monosynaptic inhibition in Aplysia neurons: effects of contingent stimulation. Brain Research. Pinsker, H. 1977. Aplysia bursting neurons as endogenous oscillators: I. Phase response curves for pulsed inhibitory synaptic input. J. Neurophysiol.